There's the shred neck, which I really haven't used personally:

http://www.shredneck.com/

And then there's products like these, which I haven't used either:

http://www.musiciansfriend.com/navigation/finger-fitness?N=100001+201726&Ntk=All&Ntt=finger&Nty=1

I'd suggest getting finger strength and dexterity the old fashioned way as much as possible. Perhaps you could bring your guitar with you to work and just fret notes with your left hand?

-Bryan